This proposal presents an academic-industrial partnership to develop an instrument for 2-photon laser scanning microscopy (2p-LSM) in non-human primates (NHP) for transformative basic science and clinical translation. Our team combines academic strengths in neuroscience and neural engineering at New York University (PI Pesaran, co-I's Movshon and Peron) and industrial engineering at ThorLabs (led by Jeff Brooker, Vice-President of Life Sciences) to translate recent advances in 2p-LSM imaging by Karel Svoboda and his group at Janelia Research Campus to the monkey. Many researchers who study the primate brain would like to add 2p-LSM to their experimental toolkit. Unfortunately, no existing microscope can be used for NHP work without significant customization due to the size and shape of the primate brain. We plan to design an instrument that will overcome these challenges and serve a community of researchers. Recently, a 2-photon random-access mesoscope, or 2p-RAM, has been developed. The 2p-RAM has the same spatial resolution as a standard 2p-LSM but uses a novel optical strategy to scan a 5 mm field of view, up 1 mm deep. The current 2p-RAM is designed for use in the mouse. To adapt it for NHP use, we propose to work with Thor Labs to develop a manipulator that can position the objective lens with six degrees of freedom over any optically accessible part of the cortical surface. We expect the new instrument to provide: 1- Random access scanning to image populations of neurons selected for study. In the mouse, roughly 10,000 neurons can be selected from larger populations and their activity imaged simultaneously; 2 - Motorized control to position and reposition the objective at micron spatial resolution and micro-radian angular resolution. This will allow users with different target areas to share an instrument; 3 - Dynamic access scanning to move the objective quickly and precisely to image multiple 5-mm fields of view. This will make possible integrated measurements of populations of neurons in many different brain regions; 4 - Software to control the instrument and acquire the data. In Aim 1, we develop a motorized platform for NHP-optimized imaging using the microscope and optimize the associated surgical procedures. In Aim 2, we develop a motorized platform for NHP-optimized imaging using the 2p-RAM. In each Aim, we develop software to control the instrument and acquire the data it will generate. At the end of the project, Thor Labs will develop, build, and sell the technology commercially. In addition, we will disseminate the technology openly, including documentation for instrument fabrication and user training. A key strength of our proposal will be a community of users with stated interest in using the device and we provide many letters of support. This instrument will be a major advance for research on the primate brain and will drive advances in human health.